Fuel systems for modern internal combustion engines typically employ either 1) port fuel injection (PFI) where fuel is injected into an air intake manifold of the internal combustion engine at relatively low pressure (typically below about 500 kPa) and subsequently passed to the combustion chamber of the internal combustion engine or 2) gasoline direct injection (GDi) where fuel is injected directly into the combustion chamber of the internal combustion engine at relatively high pressure (typically above about 14 MPa). However, some fuel systems have been developed which employ both PFI and GDi in order to take advantage of operating modes where PFI provides operational benefits and in order to take advantage of operating modes where GDi provides operational benefits. Consequently, only the PFI may be utilized under some operating conditions while only GDi may be utilized under other operating conditions. One example of a fuel system which employs both PFI and GDi is described in U.S. Pat. No. 7,263,973 to Akita et al.; however, a disadvantage of the system of Akita et al. is that when only the PFI system is used, the high-pressure fuel pump used to pressurize the fuel in the GDi system continues to be cycled by a camshaft of the internal combustion engine. This cycling, along with the close proximity of the high-pressure fuel pump to the internal combustion engine, causes fuel in the high-pressure fuel pump to elevate in temperature and potentially create vapor in the GDi system which is undesirable for the high-pressure fuel pump and which may hinder fueling when the GDi system is used.
U.S. Pat. No. 8,973,556 to Hoefner et al. describes another fuel system which employs both PFI and GDi. Hoefner et al. provides an arrangement where fuel that is used in both the PFI system and GDi system is first supplied to a drive section of the high-pressure fuel pump. Consequently, when only the PFI system is used, fuel flows through the drive section of the high-pressure fuel pump, thereby providing lubrication and cooling to the high-pressure fuel pump. While the arrangement Hoefner et al. may be effective, improvements and alternatives in any art are sought and may be desirable.
What is needed is a fuel system which minimizes or eliminates one or more of the shortcomings as set forth above and provides an alternative to the fuel systems as set forth above.